[论文解读] BVRI Photometric Observations, Light Curve Solutions and Orbital Period Analysis of BF Pav

Atila Poro, Fahri Aliçavuş+8 more|arXiv (Cornell University)|Aug 11, 2020

Stellar, planetary, and galactic studies参考文献 47被引用 8

一句话总结

本研究基于澳大利亚和阿根廷天文台的数据，提出了W UMa型触碰双星BF Pav的新型BVRI测光光变曲线解和轨道周期分析。利用Wilson-Devinney代码结合蒙特卡洛误差分析，确定了其测光质量比为1.460 ± 0.014，充满度因子为12.5%，轨道周期每世纪增加0.142秒，并在O-C图中发现18.3年的振荡周期，提示可能存在第三颗天体。

ABSTRACT

A new ephemeris, period change analysis and light curve modeling of the W UMa-type eclipsing binary BF Pav are presented in this study. Light curves of the system taken in BVRI filters from two observatories in Australia and Argentina were modeled using the Wilson-Devinney code. The results of this analysis demonstrate that BF Pav is a contact binary system with a photometric mass ratio q=1.460+_0.014, a fillout factor f=12.5%, an inclination of 87.97+_0.45 deg and a cold spot on the secondary component. By using the distance modulus formula, the distance of BF Pav was calculated to be d=268+_18 pc which is in good agreement with the Gaia EDR3 distance. We obtain an orbital period increase at a rate of 0.142 s/century due to a quadratic trend in the O-C diagram. Also, an alternative sudden period jump probably has occurred which could be interpreted as a rapid mass transfer from the lower mass star to its companion about DeltaM=2.45*10^(-6) Msun. Furthermore, there is an oscillatory behavior with a period of 18.3+_0.3 yr. Since BF Pav does not seem to have significant magnetic activity, this behavior could be interpreted as the light-time effect caused by an undetected third body in this system. In this case, the probability for the third body to be a low mass star with M>=0.075 Msun or a brown dwarf is 5.4% and 94.6% respectively. If we assume i'=90deg, a_3=8.04+_0.33 AU. The mass of the secondary component was also determined using two different methods which result close to each other.

研究动机与目标

• 利用多 epoch 的BVRI测光数据，确定W UMa型双星BF Pav的测光参数和轨道元素。
• 通过O-C图分析轨道周期变化，以检测长期趋势和周期性行为。
• 通过推导绝对参数（包括质量比、充满度因子和距离）来探讨BF Pav的演化状态。
• 鉴于O-C图中观测到的振荡行为，通过光行时效应探讨第三颗天体的存在。

提出的方法

• 从两个天文台——澳大利亚的Congarinni天文台和阿根廷的CASLEO——使用CCD和标准滤光片获取了BVRI光变曲线。
• 采用Wilson-Devinney代码对光变曲线进行建模，并利用蒙特卡洛模拟估算参数不确定性。
• 利用观测得到的极小时刻构建O-C图，以检测周期变化和振荡行为。
• 通过距离模数公式计算BF Pav的距离，并与Gaia EDR3视差进行比较。
• 假设光行时效应，对第三颗天体进行建模，假设倾角i’ = 90°，并推导其轨道元素。
• 采用两种独立方法确定次星质量，结果一致。

实验结果

研究问题

• RQ1 基于新的BVRI光变曲线，BF Pav的W UMa型双星的最新测光和轨道参数是什么？
• RQ2 BF Pav的轨道周期是否存在长期增加或周期性变化的证据？
• RQ3 O-C图中观测到的18.3年振荡的性质是什么？是否可能由第三颗天体引起？
• RQ4 所推导的质量比、充满度因子和倾角如何支持将BF Pav分类为W型触碰双星？
• RQ5 BF Pav的距离是多少？与Gaia EDR3测量值相比如何？

主要发现

• BF Pav的测光质量比确定为𝑞 = 1.460 ± 0.014，证实其为触碰双星系统。
• 充满度因子为12.5%，表明存在显著的洛希瓣溢出，与W型构型一致。
• 系统表现出每世纪0.142秒的二次周期增加，提示存在持续的质量转移或角动量损失。
• 在O-C图中检测到18.3 ± 0.3年的振荡趋势，可能由第三颗天体的光行时效应引起。
• 第三颗天体为棕矮星的概率为94.6%，若倾角为90°，其半长轴为8.04 ± 0.33 AU。
• BF Pav的距离为268 ± 18 pc，与Gaia EDR3测得的253.272 ± 0.992 pc高度一致。